Takashi Yoshimura

A 1200 V-class Fin P-body IGBT with ultra-narrow-mesas for low conduction loss

In this paper, a new 1200 V-class ultra-narrow-mesas fin p-body IGBT (U-Fin-P IGBT) is proposed. Different from the previously demonstrated fin p-body IGBT, a much narrower fin (mesa) width (~0.5 μm) is adopted in the U-Fin-P IGBT to further reduce the conduction loss; whereas the difficulty of doing emitter contact lithography on top of the ultranarrow mesa regions is resolved by using a self-aligned contact formation process design. It is found from numerical simulations that for the same turn-off energy loss, the on-state voltage drop Von (at 150°C) of the U-Fin-P IGBT is ~21% lower than that of the fin p-body IGBT. Furthermore, the U-Fin-P IGBT also shows excellent turn-on dVldt controllability.

Transient Turn-ON Characteristics of the Fin p-Body IGBT

In this paper, the transient turn-ON performance of the 1200 V-class fin p-body insulated gate bipolar transistor (Fin-p IGBT) is numerically analyzed and experimentally characterized. Analysis shows that the gate self-charging effect at the turn-ON transient of the device can effectively be suppressed due to its unique structural features of wide trenches and spacer gates. As a result, the Fin-p IGBT demonstrates excellent controllability on the turn-ON dVCE/dt of the IGBT, and hence the reverse-recovery dVKA/dt of the free-wheeling diode. Compared with conventional floating p-body IGBTs, the Fin-p IGBT can achieve a significant reduction (up to 82%) in the reverse-recovery dVKA/dt, which is of great merit in suppressing the electromagnetic interference noise. Moreover, the turn-ON energy loss of the Fin-p IGBT can be reduced by 53% compared with that of the conventional one at the same reverse-recovery dVKA/dt of 10 kV/μs.

A New Fin p-Body Insulated Gate Bipolar Transistor With Low Miller Capacitance

A new fin p-body insulated gate bipolar transistor (Fin-p IGBT) is designed and experimentally demonstrated. The device features wide trenches and spacer gates, which is implemented using a simple and low-cost process. Compared with the conventional floating p-body IGBT, the fabricated Fin-p IGBT is able to achieve remarkable reduction in both Miller capacitance (-60% at VCE of 15 V) and gate charge (-46%).

Quantification of Superiority of Broad-Buffer Diodes

We have quantitatively shown the superiority of broad-buffer (BB) diodes over conventional p–i–n diodes, especially with regard to fast and soft reverse recovery, by measuring a new quantity, Γ, signifying the degree of reverse recovery oscillation (RRO). The performance of switching devices has been evaluated in terms of the forward voltage drop VF and the reverse recovery loss ERR up to now, but these quantities cannot assess the inhibition of the RRO, which is another important property of switching devices. The quantity Γ, defined as the difference between the voltage rating and the RRO threshold power-supply voltage, represents how well the RRO is inhibited. We evaluated the performance of diodes having a variety of doping profiles in the n-drift region by numerically calculating VF, ERR, and Γ and plotting these quantities in a three-dimensional evaluation space. Our device simulation results clearly show that the values of Γ as well as VF and ERR for BB diodes are significantly lower than those for conventional diodes, and that BB diodes should be classified as a new category of diodes in view of their superior reverse recovery characteristics.